In some types of partial middle ear implantable (P-MEI) or total middle ear implantable (T-MEI) hearing aid systems, sounds produce mechanical vibrations which are transduced by an electromechanical input transducer into electrical signals. These electrical signals are in turn provided to a device which amplifies the signal and provides it to an electromechanical output transducer. The electromechanical output transducer vibrates an ossicular bone in response to the applied amplified electrical signals, thus improving hearing.
A typical single path electronic hearing assistance system for amplifying signals received from an input transducer has a single input path for receiving the signal, circuitry to produce the desired output electrical signal, and a single output path for providing the output signal to an output transducer. Such devices are useful for assisting hearing in only one ear. If a person requires assistance in both ears, two devices must be used, one for each ear.